Zwitterionic compounds and surfactants are known in the art. See Christopher M. Latham et al., Short Synthesis of Chiral 4-Substituted (S)-Imidazolinium Bearing Sulfonates and Their Use in γ-Selective Reactions of Allylic Halides with Grignard Reagents, European Journal of Organic Chemistry Volume 2012, Issue 4, pages 699-707, February 2012. U.S. Pat. No. 6,346,169 to Ikeda et al. discloses and claims a paper bulking promoter comprising amphoteric compounds. Note structure j3, which is an imidazolinium carboxylate. Notably, the amphoteric compounds disclosed do not appear to operate as debonders, Col. 2, lines 38-48. Note, also, U.S. Pat. No. 6,623,746 to Wadle et al. which discloses a variety of zwitterionic surfactants at Col. 6, lines 31 and following.
Debonder compositions are widely used in connection with the manufacture of absorbent paper products such as paper tissue and paper towel to adjust tensile strength and provide softness. Among the most effective compounds are quaternary ammonium surfactants which are sometimes used together with nonionic surfactants. Debonders are used with numerous additives such as wet strength agents and so forth. See U.S. Pat. No. 3,755,220 to Freimark et al. (1973), Col. 2, lines 1-10. U.S. Pat. No. 6,969,443 to Kokko discloses debonder compositions, including imidazolium salts in combination with nonionic surfactants. This reference also discloses the use of additives, including charge modifiers, wet strength resins, retention aids and auxiliaries such as carboxymethylcellulose. See Cols. 10-12. So also, U.S. Pat. No. 6,649,024 to Oriarian et al. discloses absorbent products incorporating a variety of cationic debonders, including di- or trialkyl ammonium salts. United States Patent Application Publication No. US2004/0163182 to Nguyen discloses nonionic surfactants used in combination with amide substituted imidazolinium salts. See paragraph [0013]. U.S. Pat. No. 4,959,125 to Spendel (1990) discloses manufacture of absorbent sheet with ampholytic or zwitterionic surfactants. See Col. 11, lines 21-46.
U.S. Pat. No. 3,686,025 to Morton (1972) discloses the use of quaternary imidazolinium salts with acyclic zwitterionic quaternary ammonium surfactants. Acyclic zwitterionic quaternary ammonium surfactants tend to be high foaming compounds which are useful for soaps/bath products; typically made with a single hydrophobic long chain which are not generally very effective as debonders in paper manufacture. Biodegradability of such compounds is also poor, making them especially undesirable for bath tissue which inevitably finds its way to septic systems.
A significant drawback of conventional systems using quaternary ammonium salts is that these compounds contribute significantly to titratable charge and change zeta potential. Controlling charge and zeta potential of the furnish in the headbox is critical to papermachine performance, especially retention of papermaking solids in the final product. The problem with adding too much cationic additive is that it will exceed the adsorption capacity of the fiber surfaces, based on either the surface area or the limited extent of negative charge of the surfaces of fibers and other solid surfaces in the furnish. Excess cationic additives beyond what adheres to the fibers is likely to cause foam, high biological oxygen demand (BOD) levels in the effluent, and poor retention and drainage. Conventional charge control agents such as carboxymethyl cellulose can adversely impact softness of the product. The use of charge control agents may be reduced or even avoided entirely when using the compositions of the present invention.